Part of my contribution to the April 2020 issue of tED Magazine was a short interview with the Illuminating Engineering Society’s Alex Baker, who has raised the alarm that lifetime claims for LED products are often misrepresented. Reprinted with permission.
Lighting manufacturers report projected service life claims for their products based on standardized testing methods, but some are reporting exaggerated claims that ultimately ignore the standard and produce market confusion. To get a handle on the issue and what electrical distributors should do when evaluating LED products, tED’s Craig DiLouie, LC, CLCP talked to Alex Baker, Manager of Government Affairs and Public Policy, Illuminating Engineering Society (IES).
DiLouie: Alex, over the past year, you’ve been raising the alarm that many lighting manufacturers have been misrepresenting—intentionally or not—lifetime claims for LED products. In a nutshell, what is the problem?
Baker: Lighting manufacturers and specifiers are playing a game of specsmanship, writing ever-increasing LED life claims that don’t make sense. In an LED lamp or luminaire, there are two primary failure mechanisms: the LED driver can and eventually will fail, and/or the luminous flux of the LEDs will depreciate or shift chromaticity (color) to an unacceptable degree. LED luminous flux depreciation is expressed in operating hours until a given threshold is reached, noted as LXX, where xx is a chosen percentage of initial light output. Claims like 200,000 or 300,000 hours to L70 (and higher) abound, but they aren’t valid or meaningful.
DiLouie: Where does the problem come from? How do the relevant IES standards LM-80 and TM-21 work, and how can they be misused?
Baker: Lifetime claims for incandescent, fluorescent, HID, and other sources were based on testing a group of lamps until 50 percent had failed. Well-designed LED products will operate for many years, making the old way of testing impractical. In 2008, the IES published the first edition of IES LM-80-08, measuring light output and color characteristics of LED packages, arrays, and modules—that is, the semiconductor devices soldered into lamps and fixtures. In 2011, the IES published IES TM-21-11, a standardized calculation for projecting luminous flux maintenance using LM-80 data. LED manufacturers run LM-80 testing typically for 10,000 hours, sometimes longer, recording measured performance data over time. With a measurement of the LEDs’ operating temperature inside a lamp or fixture, manufacturers use TM-21 to project LM-80 data beyond the measured LM-80 duration to estimate the hours until the LEDs will reach L90, L80, L70… depending on the needs of the application.
TM-21 includes one rule that is sacrosanct, critical to the correct use of the standard. It is the “6X rule,” which states that projections may not exceed six times the total LM-80 testing duration. If LM-80 testing of an LED device is reported to 10,000 hours, the longest legitimate projection is 60,000 hours to LXX. Many manufacturers seem unaware of or choose to ignore the 6X rule, though it is referenced repeatedly in the standard. Those not adhering to the 6X rule are marketing products with baseless LXX claims no more meaningful than the serial number on a DVD re-winder.
DiLouie: What problems does this create? What are the consequences for this for the customer, distributor, and industry at large?
Baker: Some of these claims are absurd. A domestic manufacturer was advertising 680,000 hours to L70 for an outdoor fixture. At 12 hours per day, that’s 155 years. C’mon. Likewise, are we supposed to believe that a luminaire’s housing, LED module, LED driver, optics, gasketing, and hardware are all going to hold up for 57 years (250,000 hours)? It’s confusing to the market when quality products with legitimate life claims are competing against exaggerated, meaningless claims.
DiLouie: What is the lighting industry doing about it? Is there any impetus for change before this becomes an even bigger future problem?
Baker: The first revisions of LM-80 and TM-21, developed by the IES Testing Procedures Committee, are now American National Standards. Adoption of ANSI/IES LM-80-15 and ANSI/IES TM-21-19, and the forthcoming IES TM-21 Calculator, should help with eliminating exaggerated luminous flux maintenance projection claims. We’re also enlisting the help of distributors, specifiers and manufacturers willing to stubbornly defend common sense.
DiLouie: What should electrical distributors do about it? How should they evaluate LED products and properly represent them to their customers?
Baker: Scrutinize LED life claims, especially anything 100,000 hours or more. Get the manufacturer’s TM-21 report for the fixture. For 100,000 hours to LXX, if the claim is legitimate, that manufacturer can also provide you the 16,700+ hour LM-80 report. If they can’t provide the correct report for the LEDs soldered within, or if they won’t produce that luminaire’s TM-21 report, or if they insist it’s okay to violate the 6X rule, you might consider steering your customers away.
I worked for an LED manufacturer for five years and the longest LM-80 report I’ve ever heard of was 18,000 hours. I’d question the relevance of longer reports; many LED device product life cycles aren’t that long.
DiLouie: Where can distributors get more information about this issue?
Baker: The Illuminating Engineering Society has many useful resources at www.ies.org, including the updated ANSI standards, an IES Position Statement regarding LED claims, articles and webinars, and TM-21-11’s Addendum B (free). Enter “TM-21” into the search function.
